This invention relates to electroacoustic transducer apparatus and more particularly to bulk mode acoustic delay line devices.
In the prior art it was known as disclosed in U.S Pat. No. 3,401,360 to provde an acoustic wave transducer having interdigital electrode elements comprising two interlaced arrays on one surface of a piezoelectric member, with provided spacing so that adjacent electrodes of the respective arrays are separated by one-quarter wavelength or odd multiples thereof. The two arrays are driven by an input signal with respect to a common electrode located on the opposite surface of the piezoelectric member and in phases displaced from each other by 90.degree. or odd multiples thereof. In effect each electrode element in an individual bulk wave transducer and each is phased differently than the adjacent electrode elements to provide the desired minimization of the higher order energy lobes and selected energy lobes.